Role of Reliability and Accelerated Testing in VHSIC Technology

In very high scale integrated circuits (VHSIC)/technology, reliability ground rules must be developed and included in chip design rules. This concept of "designed-in" reliability, rather than the traditional "tested-in" reliability approach, will be necessary in VHSIC. Accelerated testing becomes important as timely feedback on process, design, and reliability must be provided during technology development. The functional part numbers may be qualified by the technology qualification concept and by time zero functional performance verification of different part numbers. A voltage ramp test for rapid study (less than 100 h) of gate reliability of N-type metal-oxide semiconductor (NMOS) devices is discussed. HAST (highly accelerated stress test) may also be used to accelerate significantly the corrosion of the Al metallurgy of plastic encapsulated devices over the conventional temperature/humidity/bias test.